In recent years, a rise in oil price has increased the drive to enhance fuel efficiency for economic and environmental benefits.
As a result, research into reduction of weight and the enhancement of fuel efficiency through downsizing is conducted for engines and research for simultaneously securing operability and fuel efficiency competitiveness through multiple speed stages is conducted for automatic transmissions.
However, in the automatic transmission, as the number of speed stages increases, the number of internal components increase, and as a result, mountability, cost, weight, transmission efficiency, and the like may still deteriorate.
A two-way clutch is a friction member which is operated to perform functions of one-way clutch and a brake. The two-way clutch is often applied so as to perform both roles of an under drive clutch and an LR brake (low and reverse brake).
Therefore, if the two-way clutch is applied to an automatic transmission, the number of speed stages may increase, weight may be reduced, and improvements in transmission efficiency may be achieved.
However, a non-traditional control method is required for performing fail-safe operation of the two-way clutch which is differently configured than an ordinary one-way clutch.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.